Astronomers to Mark 20th Anniversary of the
Very Large Array

On August 23, scientists will mark the 20th anniversary of the National
Science Foundation's Very Large Array (VLA), the most powerful,
flexible and widely-used radio telescope in the world.

"Twenty years ago, the VLA brought dramatic new observing capabilities
to the world's astronomers, and today there is hardly a branch of
astronomy that has not been profoundly impacted by the prolific
research output of this radio telescope," said Dr. Paul Vanden
Bout, Director of the National Radio Astronomy Observatory (NRAO).

The anniversary will be marked in a ceremony at NRAO's Array Operations
Center in Socorro, NM. The keynote speaker for this ceremony will be
U.S. Senator Pete V. Domenici, R-NM. Also speaking will be
Dr. Rita Colwell, NSF Director; Dr. Anneila Sargent, president-elect
of the American Astronomical Society; Vanden Bout; Dr. Riccardo
Giacconi, president of Associated Universities, Inc. (AUI); Dr. Paul
Martin, chairman of the AUI board of trustees; and Dr. Miller Goss,
NRAO's director of VLA/VLBA operations.

"More than 2,200 researchers from hundreds of institutions around the
world have used the VLA for more than 10,000 observing projects," said
Vanden Bout. "Research conducted at the VLA has had a major impact
across the entire breadth of astronomy, from nearby objects such as
the Sun and planets of our own Solar System, to forming galaxies and
quasars billions of light-years away in the farthest reaches of the
Universe," Vanden Bout added.

Major discoveries made by the VLA have ranged from the surprising
detection of water ice on Mercury, the nearest planet to the Sun,
to the first detection of radio emission from a Gamma Ray Burster
in 1997. The VLA also discovered the first "Einstein Ring" gravitational
lens in 1987, and the first "microquasar" within our own Milky Way
Galaxy in 1994. Over the past two decades, the VLA also has made
major contributions to our understanding of active regions on the
Sun, the physics of superfast "cosmic jets" of material pouring
from the hearts of distant galaxies, the mysterious central region
of our own Galaxy, and the atmospheres of other stars, among many
others.

The results of research conducted with the VLA fill thousands of
pages in numerous scientific journals and are cited throughout
modern astronomy textbooks. In addition to such accomplishments,
the VLA also has served as a prime tool for training young astronomers.
More than 200 Ph.D degrees have been awarded by U.S. and foreign
universities based on dissertation research done using the VLA.

"Despite all these accomplishments, however, we are not simply looking
back on this occasion," said Goss. "Instead, we have prepared a detailed
plan for expanding the capabilities of the VLA, and keeping it at the
forefront of science in the 21st Century. The Expanded VLA will
incorporate new technologies to replace some of the 1970s-era equipment
that remains, and add new antennas. The result will be an astronomical
tool ten times more capable than the current VLA."

The VLA is a collection of 27 steel-and-aluminum parabolic dish antennas,
each with a dish 82 feet in diameter and weighing 230 tons. These
antennas are arranged in a giant "Y" pattern 20 miles across on the
high-desert Plains of San Agustin, 50 miles west of Socorro, New Mexico.
All 27 antennas work together as a single radio-telescope system to
produce exquisitely-detailed images of radio-emitting objects in the
Universe. Received signals from all the VLA's antennas are brought
together and computer-processed to make the images.

In the 1950s, British astronomer Sir Martin Ryle developed the
technique of using multiple, widely-separated radio-telescope antennas
working together to make images far more detailed than could be made
with any single antenna that could be feasibly built. Ryle received
the 1974 Nobel Prize in Physics for this work. In 1956, the
NSF created the National Radio Astronomy Observatory in Green Bank,
WV, and contracted with Associated Universities, Inc., a private,
nonprofit research organization, to build and operate the observatory.

"We at AUI are proud to have built and operated the NRAO -- and the VLA
-- since its beginning," said Dr. Riccardo Giacconi, the current
president of AUI and former Director General of the European Southern
Observatory. "The VLA has greatly improved our understanding
of the Universe, and the Expanded VLA will be one of the prime facilities
for meeting the challenges of 21st-Century astrophysics," added Giacconi.

While NRAO scientists and engineers were constructing and using
single-dish radio telescopes at Green Bank, they also worked on plans
for a radio-telescope array based on Ryle's technique. By 1962, the
phrase "Very Large Array" came into common use to describe this
project. The Green Bank Interferometer, a three-antenna system, began
operation in 1964, and was used extensively to gain practical
experience in operating such arrays. In addition, it made significant
scientific contributions.

In 1967, NRAO astronomers and engineers completed the first formal
proposal for a Very Large Array. The NSF submitted the VLA proposal
to Congress in 1971, and the project received Congressional
authorization in 1972. The Plains of San Agustin were selected as the
VLA site that same year.

Work at the VLA site began in 1974, and NRAO personnel began moving
to New Mexico in 1975. By October of 1975, the first VLA antenna
was complete and used to observe a galaxy 50 million light-years away
in the constellation Virgo. In 1976, two VLA antennas were used together
for the first time. In 1977, with six antennas operational, the VLA began
to be used routinely for astronomical observations. The last VLA antenna
became operational in 1980.

The VLA was formally dedicated in October of 1980, and all details
of the construction were completed in January of 1981, nearly a year
ahead of the schedule that had been prepared in 1973, and at the
budgeted cost of $78.6 million in 1972 dollars.

The National Radio Astronomy Observatory is a facility of the National
Science Foundation, operated under cooperative agreement by Associated
Universities, Inc.